Tube fitting

Abstract: A tube fitting is comprised of a tubular body (1), an annular clamping member (2), a tubular inner pipe (9), a releasing member (70), and a sealing ring (5). The clamping member is disposed axially movably in an axial bore (1A) of the body, and includes a claw (2A) and an outer peripheral portion (2E). The claw has an inclined surface projecting in a centripetal direction as an opening of the body goes away, and engages with an outer peripheral surface of a tube (8) fitted into the axial bore via the opening. The outer peripheral portion contacts with a regulatory surface (3A) of the body, and is pressed in a centripetal direction thereby, and accordingly presses the claw onto the outer peripheral surface of the tube. The inner pipe is disposed in the tube coaxially with an inner peripheral surface of the tube at an end of the tube. The releasing member includes a tubular base (7) and a leading end (4). The base is disposed axially movably in the axial bore on an outer side with respect to the regulatory surface. The leading end extends from the base over the regulatory surface to an inner side of the axial bore, and goes between the inclined surface of the claw and the outer peripheral surface of the tube. The sealing ring seals between an inner peripheral surface (10C) of the axial bore and an outer peripheral surface of the tube fixed in the axial bore.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a tube fitting, and it particularly relates to a tube fitting which can be connected with a soft or semi-hard tube without causing leakage. Description of the Related Art Figures 23 and 24, show as a matter of principle tube fittings which are designed to be connected with a soft or semi-hard tube, for example a resin tube. The tube fitting illustrated in Figure 23 comprises a tubular body 110, an annular clamping member 120, a releasing member 130, and a sealing ring 140. The body 110 includes a regulatory surface 112 on the inner peripheral surface, regulatory surface 112 which extends in the centripetal direction as an end opening 111 comes near, and an axial bore 113 into which a tube 150 is fitted via the opening 111. The clamping member 120 is disposed slidably in the axial direction on an inner side with respect to the regulatory surface 112 in the axial bore 113. The clamping member 120 includes a plurality of arms 125 which extend from a tubular end portion 124 in the axial direction, a claw 122 disposed at the free end of the arms 125, and an outer peripheral portion 123, and it is formed in an annular shape. The claw 122 has an inclined surface 121 which projects in the centripetal direction as the opening 111 goes away and which engages with an outer peripheral surface of the tube 150 fitted into the axial bore 113 via the opening 111. The outer peripheral portion 123 contacts with the regulatory surface 112 of the body 110, and thereby it is pressed in the centripetal direction by the regulatory surface 112 so as to press the claw 122 onto the outer peripheral surface of the tube 150. The releasing member 130 includes a tubular base 131 and a leading end 132. The tubular base 131 is disposed slidably in the axial direction of the axial bore 113 on the side of the opening 111. The sealing ring 140 is an 0-ring made from r-ubber, and it is disposed between the base 131 and the leading end 132 of the releasing member 130. In this conventional tube fitting, the tube 150 is fitted into the axial bore 131 via the opening 111, and it is pulled back later. Then, the outer peripheral portion 123 of the clamping member 120 is brought into contact with the regulatory surface 112 disposed in the axial bore 113 of the body 110, and it is pressed in the centripetal direction. Thus, the claw 122 is pressed onto the outer peripheral surface of the tube 150, and it pinches and engages with the outer peripheral surface of the tube 150. By the engagement between the claw 122 and the tube 150, the tube 150 is engaged with the body 110. The sealing ring 140 seals between the outer peripheral surface of the tube 150 and the inner peripheral surface of the axial bore 113 of the body 110. On the other hand, when the base 131 of the releasing member 130 is pressed into the axial bore 113, the base 131 pushes the leading end 132 in the axial direction by way of the sealing ring 140. Accordingly, the front end of the leading end 132 is brought into contact with the inclined surface 121 of the clamping member 120, and then the inclined surface 121 is urged to the inner side of the axial bore 113 and in the centrifugal direction. Consequently, the claw 122 of the clamping member 120 is moved in the centrifugal direction, and it is separated from the outer peripheral surface of the tube 150. As a result, the tube 150 is released from the clamping member 120, and it can be pulled out of the axial bore 113 of the body 110. The other conventional tube fitting illustrated in Figure 24 comprises a tubular body 210 including an axial bore 213, an annular clamping member 220, a sealing ring 240, and an inner pipe 260. The body 210 has an opening at an end into which an annular end cover 214 is screwed coaxially. The end cover 214 has a regulatory surface 212 which extends in the centrifugal direction as it goes to the inner side of the axial bore 213. The inner pipe 260 is coaxially engaged with and fixed to the inner peripheral surface 213 of the body 210 at the end. Thus, on one of the sides of the body 210, there is formed a tubular groove 216 between the outer peripheral surface of the inner pipe 260 and the inner peripheral surface of the axial bore 213 of the body 210. The clamping member 220 and the sealing ring 240 are held coaxially in the tubular groove 216 whose opening end is plugged by the end cover 214. In this conventional tube fitting, the clamping member 220 and the sealing ring 240 are disposed in the axial bore 213 of the body 210, and accordingly there is formed a tubular space between the outer peripheral surface of the inner pipe 260 and the clamping member 220 as well as the sealing ring 240. The tube 250 is fitted into the tubular space. In a manner similar to the conventional tube fitting illustrated in Figure 24, the clamping member 120 is engaged with the outer peripheral surface of the tube 250 at its claw 221, and accordingly the tube 250 is engaged with the body 210 when the tube 250 is pulled back in the opposite direction. Additionally, in this conventional tube fitting, since the tube 250 is held between the clamping member 220 and the inner pipe 260, it is clamped with a strong clamping force. Further, when the annular end cover 214 is rotated with respect to the body 210 in the direction opposite to the screwing direction, the end cover 214 can be separated from the body 210. As a result, the tube 250 can be pulled out of the body 210. In the conventional tube fitting illustrated in Figure 23, dusts, dirts or the like are likely to remain at the sealing ring 140. Accordingly, when the tube 150 is once pulled out and it is again fitted into the body 110 in order to engage therewith, this conventional tube fitting suffers from the improper sealing at the sealing ring 140. The other conventional tube fitting illustrated in Figure 24 requires much labor to disengage the tube 250 from the body 210. Similarly to the first conventional tube fitting, dusts, dirts or the like are likely to remain at the sealing ring 240 so that the sealing is inadequate. SUMMARY OF THE INVENTION From the reference US 4,951,975 a coupling for attaching a conduit to an external member is known comprising the following elements: A tubular body including an opening disposed at an end thereof, an axial bore into which a tube is fitted via the opening, and an inner peripheral surface having a regulatory surface conically tapering in the direction of the opening. Furthermore, an annular clamping member is disposed in the axial bore on an inner side with respect to the regulatory surface, held movably in an axial direction of the axial bore, and includes a claw and an outer peripheral portion. The claw has an inclined surface conically tapering opposite to the direction to the opening and engaging with an outer peripheral surface of the tube fitted into the axial bore. The outer peripheral portion is in contact with the regulatory surface and is pressed in a centripetal direction by the regulatory surface so as to press the claw onto the outer peripheral surface of the tube. A releasing member is arranged which includes a tubular base and a leading end. The tubular base is disposed in the axial bore on an outer side with respect to the regulatory surface and held movably in an axial direction of the axial bore, wherein the leading end extends from the base over the regulatory surface to an inner side of the axial bore and goes between the inclined surface of the claw and the outer peripheral surface of the tube. Finally a sealing ring is disposed so as to seal between an inner peripheral surface of the axial bore and an outer peripheral surface of the tube fixed in the axial bore. From reference EP 0 197874 A1 another tube fitting of this kind is known. This document shows a tubular inner pipe which is disposed in a tube wherein the inner pipe is fitted onto the axial bore coaxially with an inner peripheral surface of the tube. The free end of the inner pipe is positioned so as to protrude from an opening of a body when the tube is fitted into and fixed in an axial bore of the body. In view of this state of the art it is an object of the invention to provide a tube fitting which can prevent deformations of the tube securely an which can prevent the dust, dirts or the like from intruding into the seal ring securely. This object is achieved by a tube fitting having the technical features of the enclosed patent claim 1. As described in this main claim the releasing member has two annular dust seals, namely a first annular dust seal which is disposed on an inner peripheral surface of the base and a second dust seal which seals between the opening and the outer peripheral surface of the realising member. This second dust seal according to the invention has a tubular form having a tapered surface which extends in the centripetal direction. BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the present invention and many of its advantages will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings and detailed specification, all of which forms a part of the disclosure: Figure 1 is a cross-sectional view for illustrating the arrangements of a tube fitting which is not an embodiment of the invention ; Figure 2 is a partially enlarged cross-sectional view of an other tube fitting which is not an embodiment of the invention, Figure 3 is a cross-sectional view for illustrating the arrangements of a tube fitting which also not an embodiment of the invention, Figure 4 is a partially enlarged cross-sectional view of the tube fitting according to Fig. 3 ; Figure 5 is a partially enlarged cross-sectional view of the present tube fitting according to Fig. 3, Figure 6 is a cross-sectional view for illustrating the arrangements of a First Preferred Embodiment according to the present tube fitting; Figure 7 is a partially enlarged cross-sectional view of the First Preferred Embodiment according to the present tube fitting; Figure 8 is an enlarged side view, partially in cross-sectional view, for illustrating the second dust seal of the First Preferred Embodiment according to the present tube fitting; Figure 9 is a cross-sectional view for illustrating the arrangements of a Second Preferred Embodiment according to the present tube fitting; Figure 10 is a cross-sectional view of the Second Preferred Embodiment according to the present tube fitting, which illustrates the fitting of the inner pipe into the tube; Figure 11 is a cross-sectional view of the Second Preferred Embodiment according to the present tube fitting, which illustrates the fitting of the tube into the axial bore; Figure 12 is a partial cross-sectional view for illustrating the arrangements of a Third Preferred Embodiment according to the present tube fitting; Figure 13 is a side view, partially in cross-sectional view, for illustrating the clamping member of the Third Preferred Embodiment according to the present tube fitting; Figure 14 is a perspective view for illustrating the clamping member of the Third Preferred Embodiment according to the present tube fitting; Figure 15 is a partial cross-sectional view for illustrating the arrangements of a Fourth Preferred Embodiment according to the present tube fitting; Figure 16 is a side view, partially in cross-sectional view, for illustrating the clamping member of the Fourth Preferred Embodiment according to the present tube fitting; Figure 17 is a front view for illustrating the clamping member of the Fourth Preferred Embodiment according to the present tube fitting; Figure 18 is a partial cross-sectional view for illustrating the arrangements of an Fifth Preferred Embodiment according to the present tube fitting; Figure 19 is a cross-sectional view for illustrating the arrangements of a Sixth Preferred Embodiment according to the present tube fitting; Figure 20 is a side view, partially in cross-sectional view, for illustrating the clamping member of the Sixth Preferred Embodiment according to the present tube fitting; Figure 21 is a front view for illustrating the clamping member of the Sixth Preferred Embodiment according to the present tube fitting; Figure 22 is a partial cross-sectional view for illustrating the arrangements of a Seventh Preferred Embodiment according to the present tube fitting; Figure 23 is a cross-sectional view for illustrating the arrangements of the conventional tube fitting; and Figure 24 is a cross-sectional view for illustrating the arrangements of the other conventional tube fitting. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Having generally described the present invention, a further understanding can be obtained by reference to the specific preferred embodiments which are provided herein for p-urposes of illustration only and are not intended to limit the scope of the appended claims. First Preferred Embodiment The tube fitting illustrated in Figure 1 which is not an embodiment of the invention comprises a tubular body 1 made of brass, an annular clamping member 2 made of brass, an annular rib member 3 made of brass, a sealing ring 5, a tubular inner pipe 9 made of brass, and a releasing member 70. The body 1 includes an axial bore la which extends from an opening 10a disposed at an axial end to the inner side and into which a tube 8 made of resin, such as nylon, is fitted. The axial bore 1a includes a plurality of inner peripheral surfaces. The inner peripheral surfaces have an inside diameter which differs from each other and which reduces stepwise gradually from the opening 10a to the axially inner side. Namely, the axial bore la includes, from the opening 10a to the axially inner side, a first inner peripheral surface 10b, a second inner peripheral surface 10c, a third inner peripheral surface 10d, a fourth inner peripheral surface 10e, a fifth inner peripheral surface 10f, and a sixth inner peripheral surface 10g. The inner pipe 9 is fixed in the axial bore 1a of the body 1. Specifically speaking, it is engaged with and fixed to the sixth inner peripheral surface 10g of the body 1 at a base end 9b thereof, and it is engaged with and fixed to the fifth inner peripheral surface 10f of the body 1 at a flange 9a thereof. The free end of the inner tube 9 is positioned so as to protrude from the opening 10a of the body 1, and it has a tapered free end surface 9c which extends in the centripetal direction as the free end comes near. The clamping member 2 includes a tubular portion 2d which has an outside diameter smaller than the inside diameter of fourth inner peripheral surface 10e of the body 1 but which has an inside diameter larger than the outside diameter of the tube 8, and a plurality of arms 2b which extend in the axial direction integrally from the inner peripheral end of the tubular portion 2d. At the free end of the arms 2b, there is formed a claw 2a in a triangular form in cross-section which protrudes in the centripetal direction, which is tapered to a point, and which engages with the outer peripheral surface of the tube 8 fitted into the axial bore 1a via the opening 10a. On the side of the opening 10a, the inner peripheral surface of the claws 2a is formed in an inclined surface 2c which protrudes in the centripetal direction as the opening 10a goes away. Thus, as the arms 2b are deformed elastically, each of the claws 2a of the clamping member 2 is made openable and closable or expandable and contractible in the radial direction. On the side of the free end, the outer peripheral surface of the arms 2b is made into an outer peripheral portion 2e which is brought into contact with a regulatory surface 3a of the rib member 3 later described, and which is accordingly pressed in the centripetal direction. As a result, the outer peripheral portions 2e are made press the claws 2a against the outer peripheral surface of the tube 8. The clamping member 2 is positioned at the fourth inner peripheral surface 10e in the axial bore 1a of the body 1, and it is held movably in the axial direction. Here, the claws 2a of the clamping member 2 are positioned at the third inner peripheral surface 10d. The clamping member 2 thus constructed is made by machining a rod-shaped blank. The rib member 3 is engaged with and fixed to the third inner peripheral surface 10d of the body 1. It includes a regulatory surface 3a which extends in the centripetal direction as the opening 10a of the body 1 comes near and which can contact with the outer peripheral portion 2e of the claws 2b of the clamping member 2. The releasing member 70 is constructed so that the base and the leading end according to the present invention are members independent of each other. Namely, it includes a tubular base portion 7 operating as the present base, and a leading end portion 4 operating as the present leading end. Further, a sealing ring 5 (e.g., an O-ring or the like) is disposed between the base portion 7 and the leading end portion 4. The sealing ring 5 seals between the second inner peripheral surface 10c of the axial bore 1a and the outer peripheral surface of the tube 8 fixed in the axial bore 1a. The base portion 7 and the leading portion 4 constituting the releasing member 70, and the sealing ring 5 are held movably in the axial direction on the second inner peripheral surface 10c of the axial bore 1a of the body 1. The base portion 7 includes a flange 71 which is disposed at an axial end, which protrudes in the centrifugal direction and which has an outside diameter substantially identical with the inside diameter of the second inner peripheral surface 10c. When the flange 71 is brought into contact with an annular collar 6 which is made of brass and which is engaged with and fixed to the first inner peripheral surface 10b of the axial bore 1a, the base portion 7 is prevented from disengaging from the body 1. When the base portion 7 moves toward the inner side of the axial bore 1a of the body 1, the leading end portion 4 moves to the inner side together with the sealing ring 5. The leading end portion 4 is made so that its leading end can go beyond the regulatory surface 3a of the rib member 3, and that it can enter between the inclined surface 2c of the claws 2a of the clamping member 2 and the outer peripheral surface of the tube 8. The inside diameter of the base portion 7 and the leading end portion 4 is designed to be slightly larger than the outside diameter of the tube 8. The inside diameter of the sealing ring 5 is designed to be slightly smaller than the outside diameter of the tube 8, and the outside diameter thereof is designed to be slightly larger than the inside diameter of the second inner peripheral surface 10c of the axial bore 1a. This tube fitting is assembled as follows. First, the inner pipe 9 is engaged with and fixed to the fifth inner peripheral surface 10f and the six inner peripheral surface 10g of the axial bore 1a of the body 1. Thereafter, the clamping member 2 is fitted into the fourth inner peripheral surface 10e thereof. Then, the rib member 3 is engaged with and fixed to the second inner peripheral surface 10c thereof, and the leading end portion 4, the sealing ring 5 and the base portion 7 are fitted into the second inner peripheral surface 10c in this order. Moreover, the collar 6 is engaged with the first inner peripheral surface 10b thereof. Finally, the opened end of the body 1 is crimped in the centripetal direction in order to fix the collar 6 to the first inner peripheral surface 10b, thereby completing the tube fitting. As hereinafter described, the tube 8 is fixed to the tube fitting thus constructed. First, an end of the tube 8 is fitted into the body 1 via the opening 10a. During the fitting, the tube 8 is fitted into the space between the inner peripheral surface of the base portion 7 of the releasing member 7 and the outer peripheral surface of the inner tube 9. Since the tapered free end surface 9c is formed at the free end of the inner tube 9, and since the tapered free end surface 9c guides the leading end of the tube 8, the tube 8 can be fitted into the space with ease. The tube 8 is fitted into the axial bore 1a of the body 1 until its leading end is brought into contact with the flange 9a of the inner pipe 9. Thereafter, the tube 8 is pulled back slightly in the direction opposite to the fitting direction. With this operation, the claws 2a of the clamping member 2 are fastened with the outer peripheral surface of the tube 8. Accordingly, the clamping member 2 is pulled back in the opposite direction along with the tube 8. Then, the outer peripheral portion 2e of the arms 2b is brought into contact with the regulatory surface 3a of the rib member 3, and it is pressed in the centripetal direction. As a result, as the arms 2b of the clamping member 2 are deformed elastically, each of the claws 2a thereof is pressed onto the outer peripheral surface of the tube 8, thereby pinching and engaging with the tube 8. At this moment, the inner tube 9 is present on the inner peripheral side of the tube 8, and it prevents the tube 8 from deforming in the centripetal direction. Consequently, each of the claws 2a of the clamping member 2 pinches and engages with the tube 8 securely. Thus, the tube 8 can be firmly fixed to the tube fitting. When the tube 8 goes over the claws 2a of the clamping member 2, there are formed damages extending in the axial direction on the outer peripheral surface of the tube 8. However, since the sealing ring 5 is disposed between the base portion 7 and the leading end portion 4 of the releasing member 70, and since the outer peripheral surface of the tube 8 is not damaged by the claws 2a of the clamping member 2 where it is brought into contact with the sealing ring 5, it is possible to seal reliably with the sealing ring 5. When the tube 8 is fitted into the axial bore 1a of the body 8 and fixed thereto by the clamping member 2, the inner pipe 9 is present on the inner peripheral side of the tube 8, and the free end of the inner tube 9 is positioned so as to protrude from the opening 10a of the body 1. Accordingly, adjacent to the opening 10a of the body 1, the inner tube 9 can securely prevent the tube 8 from deforming, such as bending, flattening or the like, which is associated with the flexibility of the tube 8. Accordingly, the space is less likely to form between the base portion 7 of the releasing member 7, disposed around the opening 10a of the body 1, and the tube 8 where the dusts, dirts or the like try to intrude. Consequently, it is possible to reduce the dusts, dirts or the like which intrude to the sealing ring 5. All in all it is possible to maintain the sealing function of the sealing ring 5 for a long period of time. The tube 8 is disengaged from the present tube fitting as follows. First, the base portion 7 of the releasing member 70 is pressed to the inner side of the axial bore 1a of the body 1. With this operation, the leading end portion 4 of the releasing member 70 is pushed into the inner side together with the sealing ring 5. The front end of the leading end portion 4 travels over the regulatory surface 3a of the rib member 3, and it goes between the inclined surface 2c of the claws 2a of the clamping member 2 and the outer peripheral surface of the tube 8. Then, the front end of the leading end portion 4 contacts with the inclined surface 2c of the claws 2, and it urges the inclined surfaces 2c to the inner side of the axial bore la and in the centrifugal direction. Accordingly, the clamping member 2 moves to the inner side of the axial bore 1a, and simultaneously the claws 2a move in the centrifugal direction as the arms 2a deform elastically. Finally, the claws 2a leave from the outer peripheral surface of the tube 8. Consequently, the tube 8 is released from the clamping member 2, and it can be pulled out of the axial bore 1a of the body 1. With the aforementioned simple operation, for instance, by pulling out the tube 8 after pressing the base portion 7 of the releasing member 70 into the inner side of the axial bore 1a of the body 1, it is possible to remove the tube 8 from the present tube fitting with ease. In addition, since the inner pipe 9 inhibits the tube 8 from deforming, the releasing member 70 can be easily pushed into the inner side of the axial bore 1a along the outer peripheral surface of the tube 8. Hence, the operability can be improved during the removing operation. As illustrated in Figure 2, in the above-decribed tube fitting, since the inside diameter of the sealing 5 is smaller than the inside diameter of the base portion 7, the tube 8 collides with the sealing ring 5 at an edge corner 8c of the leading end thereof. Accordingly, when keeping the tube 8 being pushed to the inner side of the axial bore 1a, the tube 8 might damage the inner peripheral surface of the sealing ring 5. Consequently, the sealing ring 5 might exhibit a deteriorated sealing property. The tube fitting illustrated in Figures 3 through 5 which is not an embodiment of the invention is provided with a first dust seal 10, operating as an auxiliary sealing ring, on the inner peripheral surface 7 of the base portion 7 of the releasing member 70. Namely, in the inner peripheral surface of the base portion 7 adjacent to the flange 71, there is formed an annular groove 11 which has an axial length larger than the diameter of the cross-section of the first dust seal 10 (i.e., thickness thereof) and in which the first dust seal 10 is accommodated. Other than these constructions, this tube fitting is arranged identically with the tube fitting described above. Hence, in addition to the operations and advantageous effects of the First Preferred Embodiment, the Third Preferred Embodiment operates and produces advantageous effects extra as hereinafter described. As can be seen from Figure 4, the tube 8, fitted between the inner pipe 9 and the base portion 7, first collides with the inner peripheral surface of the first dust seal 10 at the edge corner 8c of the leading end. When the tube 8 is kept being pushed to the inner side of the axial bore 1a, the first dust seal 10 deforms. However, during the operation, since the first dust seal 10 deforms in the axial direction within the annular groove 11 so as not to interfere with the tube 8, it is little damaged on the inner peripheral surface. At the same time, the first dust seal 10 presses the edge corner 8c of the leading end of the tube 8 in the centripetal direction, thereby contracting the tube 8 at the leading end. As a result, it is possible to inhibit the edge corner 8c of the leading end of the tube 8 from colliding with and damaging the sealing ring 5. Moreover, the first dust seal 10 can prevent the dusts, dirts or the like, which adhere on the tube 8, from intruding during the fitting of the tube 8, and it can further inhibit the dust, dirts or the like from invading by way of the outer peripheral surface of the tube 8 in advance during the service of the present tube fitting. As a result, it is possible to maintain the sealing function of the sealing ring 5 for an extremely prolonged period of time. First Preferred Embodiment In the First Preferred Embodiment according to the present tube fitting illustrated in Figures 6 through 8, instead of the collar 6 provided in the tube fitting described above, a second dust seal 13 is provided between the opening 10a of the body 1 and the outer peripheral surface of the base portion 7 of the releasing member 70. The second dust seal 13 is engaged with and fixed to the first inner peripheral surface 10b of the body 1 at the base end. On the side of the free end of the seal 13, the inner peripheral surface is provided with a tapered surface 15 which extends in the centripetal direction as the free end comes near. Other than this construction, the First Preferred Embodiment is arranged identically with those of the tube fitting described above. Hence, the First Preferred Embodiment can inhibit the dusts, dirts or the like from intruding between the opening 10a of the body 1 and the base portion 7 of the releasing member 70. As a result, the First Preferred Embodiment can maintain the sealing function of the sealing ring 5 much longer than the Third Preferred Embodiment can. Second Preferred Embodiment In the Second Preferred Embodiment according to the present tube fitting illustrated in Figures 9 through 11, the inner pipe 9 is separated from the body 1 whereas it is fixed thereto in the Forth Preferred Embodiment. Other than this construction, the Second Preferred Embodiment is arranged identically with those of the First Preferred Embodiment described above. Further, this inner pipe 9 is formed as follows. Namely, it obviates the base end 9b of the inner pipe 9 of the First Preferred Embodiment, and it has the flange 9a whose outside diameter is smaller than the outside diameter of the tube 8. In the Second Preferred Embodiment, the inner pipe 9 is fitted into the tube 8, and thereafter the tube 8 with the inner pipe 9 assembled is fitted into the axial bore 1a of the body 1. Accordingly, during the fitting of the tube 8 into the axial bore 1a of the body 1, the inner pipe 9 can inhibit the tube 8 from deforming which results from the flexibility of the tube 8. Consequently, it is possible to quickly and securely fit the tube 8 into the axial bore 1a. As a result, it is possible to improve the fitting of the tube 8 in terms of operability. Third Preferred Embodiment In the Third Preferred Embodiment according to the present tube fitting illustrated in Figures 12 through 14, the body 1 includes a plurality of inner peripheral surfaces which have an inside diameter differing from each other and reducing stepwise gradually from the opening 10a to the axially inner side. Namely, the body 1 includes, from the opening 10a to the axially inner side, a first inner peripheral surface 10b, a second inner peripheral surface 10c, a third inner peripheral surface 10d, a fourth inner peripheral surface 10e, a fifth inner peripheral surface 10f, and a sixth inner peripheral surface 10g. Further, there is formed a tapered projection 10j at a stepped portion 10i between the fourth inner peripheral surface 10e and the fifth inner peripheral surface 10f. The tapered projection 10j extends in the centripetal direction as the opening 10a comes near. Furthermore, there is formed a projection 10k on the sixth inner peripheral surface 10g. The projection 10k projects in the centripetal direction, and it contacts with an end of the tubular inner pipe 9 which is free from the flange 9a and which is engaged with and fixed to the sixth inner peripheral surface 10f. In this Third Preferred Embodiment, a clamping member 20 is held movably on the inner side with respect to the rib member 3 which is engaged with and fixed to the third inner peripheral surface 10d. As illustrated in Figures 13 and 14, this clamping member 20 has a cut-off 21 which is inclined over the full length from an end to the other end in the axial direction, and it is formed in a tubular shape which has a letter "C" shape cross-section, which exhibits spring elasticity enabling to diametrically expand and contract. Further, the clamping member 20 includes a first claw 22 disposed at an axial end (e.g., on the side of the opening 10a of the axial bore 1a), and a second claw 23 disposed at an opposite axial end (e.g., on the inner side of the axial bore 1a). The first claw 22 protrudes from the inner peripheral surface in the centripetal direction in a triangular form in cross-section which is tapered to a point, and it extends in the circumferential direction. Likewise, the second claw 23 protrudes from the inner peripheral surface in the centripetal direction in a triangular form in cross-section which is tapered to a point, and it extends in the circumferential direction. Furthermore, on the side of the opening 10a, the inner peripheral surface of the first claw 22 is formed in a first inclined surface 22a which protrudes in the centripetal direction as the opening 10a goes away. Moreover, on the inner side of the axial bore 1a, the inner peripheral surface of the second claw 23 is formed in a second inclined surface 23a which protrudes in the centripetal direction as the opening 10a comes near. In addition, the outer peripheral surface of the clamping member 20 is formed in the following manner. At the intermediate portion, there is formed a central outer peripheral surface 20a which is formed flatly. On the outer peripheral surface disposed at an axial end (e.g., on the side of the opening 10 of the axial bore 1a), there is formed an outer peripheral portion 20b which extends in the centripetal direction as the opening 10a comes near and which is brought into contact with and pressed by the regulatory surface 3a of the rib member 3. On the outer peripheral surface disposed at an opposite axial end (e.g., on the inner side of the axial bore 1a), there is formed an outer peripheral surface which extends in the centripetal direction as the opening 10a goes away. Thus, the clamping member 20 is constructed so as to be symmetrical with respect to a cross-sectional plane which contains the center of the clamping member 20 in the axial direction. Other than these constructions, the Third Preferred Embodiment is arranged identically with those of the First Preferred Embodiment described above. In the Third Preferred Embodiment, the tube 8 is fixed to the tube fitting thus constructed in the following manner. First, an end of the tube 8 is fitted into the axial bore 1a until it is brought into contact with the stepped portion 10l disposed between the fifth inner peripheral surface 10f and the six inner peripheral surface 10g. Thereafter, the tube 8 is pulled back slightly in the direction opposite to the fitting direction. With this operation, the first claw 22 and the second claw 23 of the clamping member 2 are fastened with the outer peripheral surface of the tube 8. Accordingly, the clamping member 2 is pulled back in the opposite direction along with the tube 8. Then, the outer peripheral portion 20a of the clamping member 20 is brought into contact with the regulatory surface 3a of the rib member 3, and it is pressed in the centripetal direction. As a result, the clamping member 20 is contracted diametrically, and the first claw 22 and the second claw 23 are pressed onto the outer peripheral surface of the tube 8, thereby pinching and engaging with the tube 8. When disengaging the tube 8 from the present tube fitting, the base portion 7 of the releasing member 70 is pressed to the inner side of the axial bore 1a of the body 1 manually. With this operation, the leading end portion 4 of the releasing member 70 is brought into contact with the first inclined surface 22a of the first claw 22, thereby urging the inclined surface 22a to the inner side of the axial bore 1a and in the centrifugal direction. Accordingly, the clamping member 2 is moved to the inner side of the axial bore 1a, and the second inclined surface 23a of the second claw 23 are pressed and urged by the tapered projection 10j in the centrifugal direction. Consequently, the clamping member 20 is expanded diametrically, and the first claw 22 and the second claw 23 are disengaged from the outer peripheral surface of the tube 8. As a result, the tube 8 is released from the clamping member 20, and it can be pulled out of the axial bore 1a of the body 1. In the Third Preferred Embodiment, the clamping member 20 includes the first claw 22 and the second claw 23 at the axially opposite ends, respectively. The first claw 22 and the second claw 23 engage with the outer peripheral surface of the tube 8. Accordingly, an enhanced engaging force can be exerted between the clamping member 20 and the tube 8. Moreover, the clamping member 20 is constructed so as to be symmetrical with respect to a cross-sectional plane which contains the center of the clamping member 20 in the axial direction. Consequently, when assembling the clamping member 20 within the axial bore 1a of the body 1, the clamping member 20 can be assembled within the axial bore 1a by facing either of the axially opposite ends to the bore 1a. As a result, the assembly can be improved in terms of operability. Fourth Preferred Embodiment The Fourth Preferred Embodiment according to the present tube fitting illustrated in Figures 15 through 17 comprises a configurationally modified version of the clamping member 20 and the rib member 3 of the Third Preferred Embodiment. Other than this modification, the Fourth Preferred Embodiment is arranged identically with those of the Third Preferred Embodiment described above. As illustrated in Figures 16 and 17, instead of the inclined cut-off 21 of the clamping member 20 of the Third Preferred Embodiment, the clamping member 20 of the Fourth Preferred Embodiment is provided with a non-inclined cut-off 21. Moreover, the first and second claws 22 and 23 are provided with cut-offs 22c and 23c, respectively. Except these constructions, the clamping member 20 is constructed similarly to those of the clamping member 20 of the Third Preferred Embodiment described above. As illustrated in Figure 15, the rib member 3 of the Fourth Preferred Embodiment is further provided with a flat platform 3b disposed at an intermediate portion of the inclined surface 3a. The flat platform 3b has an inside diameter smaller than the outside diameter of the central outer peripheral surface 20a of the clamping member 20. Except this construction, the rib member 3 is constructed similarly to those of the rib member 3 of the Third Preferred Embodiment described above. In the Fourth Preferred Embodiment, when the tube 8 is fixed in the axial bore 1a, the outer peripheral portion 20b of the clamping member 20 is pressed in the centripetal direction by the inclined surface 3a of the rib member 3, and at the same time the central outer peripheral surface 20a is pressed securely in the centripetal direction by the flat platform 3b of the rib member 3. At the same time, the first claw 22 pinches the tube 8 mainly at the four edges 22d disposed in the circumferential direction. Similarly, the second claw 23 pinches the tube 8 mainly at the four edges disposed in the circumferential direction. Accordingly, compared with the clamping member 20 of the Third Preferred Embodiment which is provided with the claws 22 and 23 having only two edges in the circumferential direction, the engaging force exerted between the first claw 22 and the second claw 23 of the clamping member 20 and the tube 8 can be further enhanced. Fifth Preferred Embodiment In the Fifth Preferred Embodiment according to the present tube fitting illustrated in Figure 18, the body 1 includes a plurality of inner peripheral surfaces which have an inside diameter differing from each other and reducing stepwise gradually from the opening 10a to the axially inner side. Namely, the body 1 includes, from the opening 10a to the axially inner side, a first inner peripheral surface 10b, a second inner peripheral surface 10c, a third inner peripheral surface 10d, a fourth inner peripheral surface 10e, and a fifth inner peripheral surface 10f. A projection 10k projecting in the centripetal direction is disposed on the fifth inner peripheral surface 10f, and it contacts with an end of the tubular inner pipe 9 which is free from the flange 9a and which is engaged with and fixed to the fifth inner peripheral surface 10f. Further, the sealing ring 5 is held on the third inner peripheral surface 10d. Furthermore, a first rib member 3 and a second rib member 31 are engaged with and fixed to the second inner peripheral surface 10c. On the opening 10a side of the end surface of the second rib member 31, there is formed a tapered projection 31a which extends in the centripetal direction as the opening 10a comes near. Moreover, a releasing member 73 is held movably in the axial direction on the first inner peripheral surface 10b, and the second dust seal 13 is engaged with and disposed on the first inner peripheral surface 10b. As can be seen from Figure 18, in the Fifth Preferred Embodiment, the releasing member 73 is constructed so as to integrate the base and the leading end according to the present invention. Namely, it includes a thick tubular base 73a operating as the present base, and a thin tubular leading end 73b operating as the present leading end. Further, the base 73a of the releasing member 73 has a flange 73c at an axial end, flange 73c which extends in the centrifugal direction and which has an outside diameter substantially equal to the inside diameter of the first inner peripheral surface 10b. Furthermore, in the inner peripheral surface of the base 73a adjacent to the flange 73c, there is formed an annular groove 11 which has an axial length larger than the thickness of the first dust seal 10 and in which the first dust seal 10 is accommodated. Moreover, when the releasing member 73 is moved to the inner side of the axial bore la of the body 1, the leading end 73b of the releasing member 73 is constructed so that it can enter between the first inclined surface 22a of the first claw 22 of the clamping member 2 and the outer peripheral surface of the tube 8. As illustrated in Figure 18, instead of the tapered configuration at the axial ends of the clamping member 20 of the Third Preferred Embodiment, the clamping member 20 of the Fifth Preferred Embodiment is formed in an arc shape, on the outer peripheral surface. Other than this construction, it is arranged identically with those of the clamping member 20 of the Third Preferred Embodiment. Accordingly, on the side of the opening 10a, the outer peripheral surface of the clamping member 20 is constructed so as to operate as an outer peripheral portion 20b which is pressed in the centripetal direction by the regulatory surface 3a of the first rib member 3. The Fifth Preferred Embodiment thus constructed is assembled with the tube 8 in the following manner. First, an end of the tube 8 is fitted into the axial bore 1a until it is brought into contact with the stepped portion 10m disposed between the fourth inner peripheral surface 10e and the fifth inner peripheral surface 10f. Thereafter, the tube 8 is pulled back slightly in the direction opposite to the fitting direction. With this operation, the first claw 22 and the second claw 23 of the clamping member 20 are fastened with the outer peripheral surface of the tube 8. Accordingly, the clamping member 20 is pulled back in the opposite direction along with the tube 8. Then, the outer peripheral portion 20b of the clamping member 20 is brought into contact with the regulatory surface 3a of the first rib member 3, and it is pressed in the centripetal direction. As a result, the clamping member 20 is contracted diametrically, and the first claw 22 and the second claw 23 are pressed onto the outer peripheral surface of the tube 8, thereby pinching and engaging with the tube 8. When disengaging the tube 8 from the present tube fitting, the base 73a of the releasing member 73 is pressed to the inner side of the axial bore 1a of the body 1 manually with a hand or fingers. With this operation, the leading end 73b of the releasing member 73 is brought into contact with the first inclined surface 22a of the first claw 22, thereby urging the inclined surface 22a to the inner side of the axial bore 1a and in the centrifugal direction. Accordingly, the clamping member 20 is moved to the inner side of the axial bore 1a, and the second inclined surface 23a of the second claw 23 of the clamping member 20 is pressed and urged by the tapered projection 31a of the second rib member 31. Consequently, the clamping member 20 is expanded diametrically, and the first claw 22 and the second claw 23 are disengaged from the outer peripheral surface of the tube 8. As a result, the tube 8 is released from the clamping member 20, and it can be pulled out of the axial bore 1a of the body 1. Sixth Preferred Embodiment In the Sixth Preferred Embodiment according to the present tube fitting illustrated in Figures 19 through 21, a clamping member 40 is formed by drawing. Other than this modification, the Sixth Preferred Embodiment is arranged identically with those of the First Preferred Embodiment. For instance, the clamping member 40 of the Sixth Preferred Embodiment is made as follows. First, a plate-shaped blank having a plurality of slits is drawn to a tubular preform. Then, the tubular preform is bent in the centripetal direction at an axial end so as to form a plurality of claws 43 later described. As can be appreciated from Figures 20 and 21, the clamping member 40 includes a tubular portion 41 which, as best shown in Figure 20, has an outside diameter smaller than the inside diameter of the fourth inner peripheral surface 10e of the body 1 but which has an inside diameter larger than the outside diameter of the tube 8, and a plurality of arms 42 which extend in the axial direction integrally from the inner peripheral end of the tubular portion 41. At the free end of the arms 42, there is formed a claw 43 which is made by bending in the centripetal direction. On the side of the opening 10a, the inner peripheral surface of the claws 43 is made into an inclined surface 43a which protrudes in the centripetal direction as the opening 10a goes away. Thus, as the arms 42 are deformed elastically, each of the claws 43 of the clamping member 40 is made openable and closable or expandable and contractible in the radial direction. On the free end side of the arms 42, the outer peripheral surface of the arms 42 is made into an outer peripheral portion 42a which is brought into contact with the regulatory surface 3a of the rib member 3, and which is accordingly pressed in the centripetal direction so as to press the bent portion of the claws 43 onto the outer peripheral surface of the tube 8. The Sixth Preferred Embodiment operates and produces advantageous effects similarly to the First Preferred Embodiment described above. In addition, in the Sixth Preferred Embodiment, since the clamping member 40 is made by drawing a plate-shaped blank to a tubular preform and thereafter by bending the tubular preform in a centripetal direction at an end, the clamping member can be manufactured without employing time-consuming machining and without causing material loss. Accordingly, it can be manufactured with inexpensive manufacturing costs and with ease. Seventh Preferred Embodiment In the Seventh Preferred Embodiment according to the present tube fitting illustrated in Figure 22, the length of the inner tube 9 is enlarged so as to project its free end from the end of base 7 of the releasing member 70. Other than this modification, the Seventh Preferred Embodiment is arranged identically with those of the First Preferred Embodiment. In the Seventh Preferred Embodiment, since the free end of the inner pipe 9 is positioned so as to protrude from the end of the base 7 of the releasing member 70 when the tube 8 is fixed in the axial bore 1a, the inner pipe 9 can inhibit the deformations, such as bending or the like, of the tube 8 further securely. Accordingly, this modification enables to inhibit the dust, dirts or the like from intruding to the sealing ring 5 further reliably.

Claims: A tube fitting, comprising: a tubular body (1) including an opening (10a) disposed at an end thereof, an axial bore (1a) into which a tube (8) is fitted via the opening (10a), and an inner peripheral surface having a regulatory surface (3a) conically tapering with the diameter reducing in the direction of the opening (10a), an annular clamping member (2) disposed in said axial bore (la) on an inner side with respect to said regulatory surface (3a), held movably in an axial direction of said axial bore (1a), and including a claw (2a) and an outer peripheral portion (2e), the claw (2a) having an inclined inner surface (2c) conically tapering with the diameter reducing opposite to the direction to said opening (10a) and engaging with an outer peripheral surface of said tube (8) fitted into said axial bore (1a), the outer peripheral portion (2e) contacting with said regulatory surface (3a) and being pressed in a radial direction by said regulatory surface (3a) so as to press the claw (2a) onto the outer peripheral surface of said tube (8); a releasing member (70) including a tubular base (7) and a leading end (4), the tubular base (7) disposed in said axial bore (1a) on an outer side with respect to said regulatory surface (3a) and held movably in an axial direction of said axial bore (1a), the leading end (4) extending from the base (7) into said regulatory surface (3a) to an inner side of said axial bore (1a) and going between said inclined inner surface (2c) of the claw (2) and said outer peripheral surface of said tube (8); and a sealing ring (5) disposed so as to seal between an inner peripheral surface of said axial bore (1a) and an outer peripheral surface of said tube (8) fixed in said axial bore (1a), characterized in that a tubular inner pipe (9) is disposed in said tube (8), said pipe (9) being fitted into said axial bore (1a), at an end of said tube (8), coaxially with an inner peripheral surface of said tube (8); wherein said releasing member (70) further includes a first annular dust seal (10) which is disposed on an inner peripheral surface of said base (7) and which seals between the inner peripheral surface of said base (7) and an outer peripheral surface of said tube (8) and said body (1) includes a second dust seal (13) which seals between said opening (10a) and an outer peripheral surface of said releasing member (70), said second dust seal being a generally cylindrical shape extending axially along said releasing member. The tube fitting according to claim 1, wherein a free end of said inner pipe (9) is positioned so as to protrude from said opening of said body (1) when said tube (8) is fitted into and fixed in said axial bore (1a) of said body (1). The tube fitting according to claim 1, wherein a free end of said inner pipe (9) is positioned so as to protrude from an end of said base (7) of said releasing member (70) when said tube (8) is fitted into and fixed in said axial bore (1a) of said body (1). The tube fitting according to claim 1, wherein said inner pipe (9) is separable from said body (1), and it is fitted into said tube (8) before said tube (8) is fitted into said axial bore (1a) of said body (1). The tube fitting according to claim 1, wherein said inner pipe (9) is fixed in said axial bore (1a) of said body (1) coaxially therewith. The tube fitting according to claim 1, wherein said sealing ring (5) is disposed between said base (7) and said leading end (4) of said releasing member (70). The tube fitting according to claim 1, wherein said sealing ring (5) is disposed on an inner side with respect to said clamping member (2) in said axial bore (1a) of said body (1). The tube fitting according to claim 1, wherein said clamping member (2) includes said claw (2a) which is disposed at axially opposite ends of said clamping member (2), respectively. The tube fitting according to claim 8, wherein said clamping member (2) is constructed so as to be substantially symmetrical with respect to a cross-sectional plane which contains a center of said clamping member (2) in an axial direction thereof. The tube fitting according to claim 1, wherein said clamping member (2) is made by drawing a plate blank to a tubular preform and thereafter by bending the tubular preform in a centripetal direction at an end. The tube fitting according to claim 1, characterized in that said second dust seal (13) has an inner peripheral surface which is provided with a tapered surface (15) extending in the centripetal direction as the free end of the second dust seal (13) approaches the outer peripheral surface of the tubular base (7). The tube fitting according to claim 1, characterized in that said second dust seal (13) is engaged with and fixed to the inner peripheral surface (10b) of the tubular body (1).

Inventors: HOSOYA KINJI, KUMAGAI TOSHIHIRO, TAKAYANAGI AKIRA, HOSOYA, KINJI, KUMAGAI, TOSHIHIRO, TAKAYANAGI, AKIRA, HOSOYA, KINJI, C/O KABUSHIKI KAISHA AOI, KUMAGAI, TOSHIHIRO, C/O TOKAI RUBBER IND., LTD., TAKAYANAGI, AKIRA, C/O TOKAI RUBBER IND., LTD.
Applicants: A0I KK, TOKAI RUBBER IND LTD, KABUSHIKI KAISHA A0I, TOKAI RUBBER INDUSTRIES, LTD.
Application year: 1994
Main classification: F16L37
IPC codes: F16L33, F16L37